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I-88 (I-355 to Mitchell Road) Congestion and Crash Scans

The Chicago region traffic congestion scans were created by averaging five minute speed data obtained from freeway loop detectors, radar, and mobile technology data. The traffic scans display average speed on a freeway corridor as a function of time of day (the x-axis) and location (the y-axis) along a freeway corridor.

Crash scans show the rate of total highway crashes per 100 million vehicle-miles traveled (VMT) for 1/10 mile segments.  The purpose of these crash scans is to show highway planners and system managers how crashes are related to congestion.  Understanding where crashes are concentrated can help planners and engineers focus on improving those locations with the worst performance.  

Congestion Scan

I-88, Reagan Memorial Tollway Mitchell Road to I-355 Congestion Scan, 2011. Showing average speed by milepost by time of day.

Download hi-res PDF

Crash Scan

I 88, Ronald Reagan Tollway, Mitchell Road to I-355 crash scan, 2008-12. Showing number of crash rates per 100 million vehicle miles traveled.

Performance Data

Non-holiday Tuesdays, Wednesdays, and Thursdays:

East-bound I-88/Reagan Memorial Tollway

Measure 2010 2011
Free-Flow Travel Time
(Minutes)
13.73 14.23
Average AM Peak-Period
Travel Time (Minutes)
14.86 16.93
AM Travel Time Index 1.08 1.19
Average PM Peak-Period
Travel Time (Minutes)
14.36 14.89
PM Travel Time Index

1.05

1.05
AM Peak-Period
95th Percentile Travel Time
(Minutes)

17.82

24.26

AM Peak-Period
Planning Time Index

1.30

1.70
PM Peak-Period
95th Percentile Travel Time
(Minutes)

15.04

15.59
PM Peak-Period
Planning Time Index

1.10

1.10
Congested Hours

0.51

1.65

West-bound I-88/Reagan Memorial Tollway

Measure

2010

2011
Free-Flow Travel Time
(Minutes)

13.80

13.89
Average AM Peak-Period
Travel Time (Minutes)

14.54

14.73
AM Travel Time Index

1.05

1.06
Average PM Peak-Period
Travel Time (Minutes)

14.65

15.49
PM Travel Time Index

1.06

1.12
AM Peak-Period
95th Percentile Travel Time
(Minutes)

15.60

15.76

AM Peak-Period
Planning Time Index

1.13

1.13
PM Peak-Period
95th Percentile Travel Time
(Minutes)

16.76

19.10
PM Peak-Period
Planning Time Index

1.21

1.38
Congested Hours

0.52

1.09

 

About the Data

Data provided by IDOT, Illinois Tollway, and HERE. 

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